Foot-propelled wheeled hobby or sport device

ABSTRACT

The invention relates to a foot-propelled, wheeled hobby and/or sport device that has a foot plate. Characteristic of the device is that it has one or two wheels ( 1 ) positioned between two side plates ( 7, 8 ) the axle ( 3 ) of which wheel ( 1 ) is fixed to the side plates ( 7, 8 ). Positioned under the wheel ( 1 ) axle ( 3 ) there are foot plates ( 9, 10 ) extending outwards connected to the side plates ( 7, 8 ). During the normal use of the device the side plates ( 7, 8 ) extend above the knee ( 21 ) of the person using the device, who is standing on either one or both of the foot plates ( 9, 10 ).

The invention relates to a foot-propelled, wheeled hobby and/or sportdevice and an auxiliary structure used with it. Favoured devices forspending free time involving physical movement are the variousstructures rolling on wheels and powered by the legs, of which the mostwidespread for decades all over the world is the traditional bicycle,which involves sitting on a saddle and making it move via pedals.Besides bicycles, which are of a relatively complex structure and largenumerous other, simpler and smaller wheeled hobby devices powered by thelegs making it possible to carry out a sport-like hobby activity suchroller skates, which are affixed to the user's feet, or the two-wheeledscooter, which has handlebars similar to those of a bicycle and a long,thin plate to which the wheels are fixed in the front and at the rear,and the user stands on the plate with one foot while the other footpowers the scooter. Used to an increasing extent is the so-calledskateboard, which has four wheels with a small diameter, and standing onit the user drives it with movements as with the scooter, and on aninclined surface the user may stand on the board with both feet and rollforwards using the body to maintain balance. Finally we mention thatthere exists a pedal-powered sport or hobby device that has a singlespoked wheel of the type used on bicycles the use of which, however,requires—balancing—skills in the individual that very few persons have,so it was not able to become a product that was used to a great extent,not even in a form stabilised with servo motors, which, naturally,increases the manufacturing costs to no small degree.

We would like to remark in connection with the aforementioned skateboardthat, although it is an extensively favoured hobby device—it is ratherslow and less manoeuvrable, as the resistance of its four small wheelsis very large. Besides this there are exception to the skateboard fromthe point of view of safety, because if the user falls, for example, orgets of the sport device for other reasons, the device becomes free and,for example, on an inclined public road it may roll further on and causean accident.

The task to be solved with the invention is to provide a foot-propelled,wheeled hobby and/or sport device which makes movement and poweringpossible similar to that in connection with the skateboard, but whichis, however, significantly faster, more manoeuvrable, more easilydirected and more favourable from a point of view of safety.

The basis of the invention is the recognition that with the use of asingle, for example, spoked wheel with a rubber tyre of a size of thoseused for bicycles a hobby and/or sport device that is propelled by thefeet as when using a scooter may be created the user of which mayprogress at lower or higher speeds as long as the wheel is surrounded bya yoke in which the wheel axle is fitted in bearings, and the yoke hasat least one foot-rest element, favourably one extending on either side,far under the wheel axle, close to the pavement on which the wheelrolls, on which or on one of which the user of the device stands withone leg while propelling the device with the other. Furthermore, werecognised that such a device may be set up with two wheels positionedimmediately next to each other displaced in the lateral direction ascompared to each other if the wheels are connected in the longitudinaldirection, and are fitted in the lateral direction so that they mayrotate with respect to each other.

On the basis of this recognition the set objective has been solved witha foot-propelled, wheeled hobby and/or sport device according to theinvention that has a foot plate and characteristics of the deviceinclude

-   -   it has a wheel positioned between two side plates the axle of        which wheel is fixed to the side plates;    -   positioned under the wheel axle there are foot plates extending        outwards-connected to the side plates;    -   during the normal use of the device the side plates extend above        the knee of the person using the device, who is standing on        either one or both of the foot plates. In the interest of        increasing the stability of the device it is practical if the        side plates are fixed together as a yoke via a connection rib or        ribs running along their edges.

According to another construction example the ends of the wheel axle arefixed into the thickened plate parts of the side plates, fitted intothem.

It is favourable, furthermore, if the foot plates are positioned at amaximum distance from the axle of the wheel ensuring perfect function ofthe device practically at a distance from ground level in the operatingposition of the device that makes function possible, advantageously atthe same level.

Characteristic of another embodiment of the device is that the sideplates are circular plates of a form and size that essentially conformsto that of the form of the wheel, and the curved, convex, as seen fromthe outside, connection rib runs without interruption along the edges ofthe side plates—except for an opening allowing the wheel rim toprotrude.

According to a further invention criterion the side plates are formed sothat they only partly cover from the side of the wheel, advantageouslyin such a way that in the vicinity of the wheel axle their width is thesmallest, and from this range their width increases downwards andupwards.

A construction form may be advantageous if it has a bearing housingsurrounding the axle and a wheel rim with a rubber pneumatic tyre, whichwheel is connected to the bearing housing by spokes; furthermore, if thedevice has handlebars that are directly or indirectly connected to theside plates.

According to another invention criterion at the height of the shins ofthe person using the device there is a supporting plate fixed to each ofthe side plates parallel to the axle.

Another foot-propelled, wheeled hobby and/or sport device with a footplate also forms the subject of the invention, and characteristics ofthis device include

-   -   it has two parallel wheels separated by a distance, positioned        displaced from one another in side view, which are connected to        each other by a connection element that prevents movement in the        longitudinal direction with respect to one another, but permits        rotation as compared to one another;    -   the bearing housing of the axles of the wheels protrude from the        plane of the wheels, and supporters are fixed to these        protruding bearing housing parts;    -   foot plates are fixed to the lower parts of the supporters, and        above these there are side plates fixed to the supporters        extending above the knees of the user while the device is in        use. It is practical if the device has an upside-down V shaped,        from side view, Z shaped, from above, connection element with        displaced curved legs connected to one another with a connection        rib falling in the plane of the wheels and, in a practical case,        horizontal from above, from the lower end of each of the legs        there is a vertical pin protruding downwards; and these pins fit        into bearings fixed into the part of the bearings of the wheel        axles that protrude inwards from the wheel plane. It is        advantageous, furthermore, if the device has curved supporters        which extend above to the upper range of the wheels. According        to another invention criterion the wheels are displaced with        respect to one another to an extent that the contour line of the        one wheel is positioned in the vicinity of the axle of the other        wheel, in a practical case with a separation equivalent to 1-5%        of the diameter of the wheel. It is practical if the wheels are        braced to each other with one or more springs—so that they may        rotate from each other contrary to the spring force; and the        device has blocks preventing the wheels that have been pushed        back into their basic position by the spring or springs from        touching one another. In this case it is advantageous if the        springs are positioned on the lower and upper part of the        device, in a practical case the upper edges of the side plates        are connected with two springs, and one spring is inserted        between the foot plates. It may also be a good feature if there        are blocks on the inner side of the lower ends of the connection        element legs; and also if there are blocks on the outer sides of        the bearings receiving the vertical pins.

The subject of the invention also relates to an auxiliary structure tobe used with the above hobby and/or sport device for the reduction ofthe friction between the person using the device and the side plates,the essence of which is that there is a cart-like structure that may befixed to the knee of the person using the device with a releasableconnection, into which there are protruding rollers embedded in the sideturned towards the side plate and the side opposite this side is asurface curved to match the shape of the knee. A characteristic of anembodiment of the auxiliary structure is that if in side view thecart-like structure has a rectangular—in a given case with roundedcorners—base, in the corner vicinities of which there are hollows formedin the plane surface and into these hollows the axles of the rollers arefitted, and the opposite side is curved in shape. It is practical if therollers protrude 1-3 mm out of the, preferably, plane surface turnedtowards the side plate. It may also be advantageous if the cart-likestructure has brace(s) consisting of hook and loop brace-parts.

In the following the invention will be presented in detail on the basisof the attached drawings, which contain advantageous constructionexamples of the foot-propelled, wheeled hobby and/or sport device andsome structural part-solutions. In the drawings

FIG. 1 shows a construction form of the device in side view with theperson using and standing on it;

FIG. 2 shows the cross section of the device according to FIG. 1 takenthrough the wheel axle;

FIG. 3 separately shows the yoke forming a part of the device insketched cross section;

FIG. 4 shows another construction form of the device according to FIG. 1together with a person using the device who is standing on the devicewith his/her left foot and propelling it with his/her right;

FIG. 5 shows the phase of the use of the device according to FIG. 4 whenthe person using it is standing on it with his/her right foot andpropelling it with his/her left;

FIG. 6 shows an auxiliary structure making the use of the device easierin sketched rear view;

FIG. 7 shows the side view of an element of the auxiliary structureaccording to FIG. 6;

FIG. 8 shows the cross section taken along the line A-A marked on FIG.7;

FIG. 9 shows a further construction form of the hobby and/or sportdevice in side view, without side plates;

FIG. 10 shows the device according to FIG. 9 fitted with side plates;

FIG. 11 shows the view seen from the direction B marked on FIG. 9;

FIG. 12 shows the view seen from the direction C marked on FIG. 9;

FIG. 13 shows the device according to FIG. 9 in plan view, without theconnection element that connections the wheels;

FIG. 14 shows the side view of the connection element;

FIG. 15 shows the front view of the connection element;

FIG. 16 shows the plan view of the connection element, also showing thewheel-rotation possibility with dotted lines.

The whole hobby and/or sport device seen on FIGS. 1 and 2 has a wheelwith reference number 1, which, for example, is the same as atraditional spoked bicycle wheel, or may be of a construction similar tothat. In accordance with this it has a central axle 3 and a bearinghousing 6 surrounding this, which is connected by spokes 5 marked withdotted lines to a wheel rim 2 a, which has—in a way known in itself—apneumatic rubber tyre 2 fitted to it. (For the purpose of clarity wehave only drawn in a few spokes 5 in FIG. 1.) The geometric axis ofrotation of the wheel 1 has been marked with the reference letter x.

In the sense of the invention the device has a yoke 4 that carries outthe transfer of the load of the mass of the person using the device 15within the circumference of the wheel 1 far under the geometric axis ofrotation x, which from the point of view of its cross section (FIG. 2)is an upside-down U shaped, box-like element with its legs pointingdownwards, which in the case of this construction example hasessentially round, when seen from side view, plane side plates 7, 8.Here the side plates 7, 8 are only “essentially” round, because in themiddle of their lower end part a sector-shaped part with length h ismissing (FIG. 1), which, as can be seen in FIG. 3, has a height m. Asthe side plates 7, 8 are connected to each other by a curved connectionrib 14, protruding when seen from the outside, which extends along themajority of the circumference of the side plates 7, 8—in other words itextends to the two end points of the “cut out” sector-shaped part wehave already mentioned—as rigid, box-like yoke 4 is formed on the lowerpart of which there is an opening 11 (see also FIGS. 1 and 2), which haslength h, width b, and the edge of which lies at a height m above theground level t—pavement—when the person 15 shown on FIGS. 1 and 2 usesthe device in the proper manner. If the total height of the device abovethe ground level t is H, the geometric axis of rotation x of the wheel 1is positioned at a height H/2 above the ground level t. The axle 3 ofthe wheel 1 shown in FIGS. 1 and 2 is fixed rigidly into the thickenedplate parts 7 a, 8 a of the side plates 7, 8 by its ends, and it ispractical if these thickened plate parts 7 a, 8 a are so positioned thatthe geometric axis of rotation x goes through their centre points. Theaxle 2—in the usual way—may be constructed from steel, and the yoke 4from glass fibre polyester; this material, in the case that itsthickness is sufficiently dimensioned, may provide a secure fixation forthe axle 3.

The lower foot plates 9, 10 protruding outwards on both side areconnected directly to the side plates 7, 8, in a practical case formedas one element with the yoke 4, in other words these are plates thatprovide support for the one or the other foot, the person using thedevice 15 stands—leans on—with one foot on one of them, while the otherfoot propels the device with intermittent kicking movements from groundlevel t similar to those when using a scooter. The supported foot andthe propelling foot may even swap roles while in motion. As it can beseen in FIG. 1 from side view the foot plates 9, 10 are positioned inthe range within the circumference of the wheel 1, and as far aspossible under the geometric axis of rotation x. The height of the sideplates 7, 8, in other words the yoke 4 is selected so that its upperedge extends above the knees 21 of the person using the device 15, whenhe/she is using the device in the proper manner (FIG. 1).

The stability of the device during use is greater, the greater thedistance c is, in other words the foot plates 9, 10 are positioned asdeeply as possible under the axis of rotation x, that is the distance mbetween the ground level t, the surface of the pneumatic rubber tyre 2rolling on it, and the foot plates 9, 10; so via the yoke 4 the personusing the device 15 load the axle 3 of the wheel 1 under the geometricaxis of rotation x, close to the most external circumference line of thewheel 1, almost touching the ground level t. We would like to mentionthat it is most practical if the foot plates 9, 10 start out from thelongitudinal edges of the opening 11, in other words those perpendicularto the geometric axis of rotation x, and are formed as the outward bentcontinuations of the side plates 7, 8, but, naturally, they may bepositioned higher.

We mention here that the device according to FIGS. 1-3 has a yoke 4basically for considerations of stability, the device has side plates 7,8 and foot plates 9, 10, which are of determinant significance from thepoint of view of the operation of the device. As the composite actionbetween the foot of the person using the device 15 eccentrically loadingthe device and the wheel 1 is produced by the friction force occurringbetween the one of the side plates 7, 8 and the shin as a result of thehorizontal reaction force of the torque created by the eccentric loadforce during the swapped (or one sided) supporting-propelling cycles.

The yoke 4 may also be supplemented with handlebars 13 of a type likethose used on bicycles with a lower forked end, which also serves betterstability in the plane of motion and the counterbalancing of theeccentric loading, and it makes the use of the device safer, sorequiring less skill, so it is only required primarily for beginnerswhile they are learning. The same thing can also be said of thesupporting plates 12 positioned parallel to the geometric axis ofrotation, to which the shin of the supporting foot can be pushed upagainst during motion. The faceplates 16 of the foot plates 9, 10 are toprevent the feet from slipping forwards, however, these are not requiredby an experienced user either.

The yoke 4 presented in detail above apart from the opening 11completely encloses the wheel 1, however, it is not essential to haveit. Partly to reduce the mass of the device and partly for the purposeof saving on material the application of the yoke 4 a that can be seenin FIGS. 4 and 5 may be advantageous, the side plates 17 of which yoke 4a are formed by cutting out a deep section from the side plates 7, 8according to FIGS. 1-3. In this way the side plates have a minimum widthe in the line of the geometric axis of rotation x and above and below—inprojection—a maximum width f and are convex seen from above and belowand concave seen from the two sides, these elements are fixed to eachother with a connection rib 18 above and two short connection ribs 19below. The width e should, naturally, be selected so that there issufficient space for the friction connection between the shin and theside plates 17.

The use of the hobby and/or sport device according to FIGS. 1-5 takesplace in the following way:

The person using the device 15—as we have already mentioned—propels thedevice with movements similar to those made when using a scooter. Theone foot—the left one according to FIG. 4—loads the device eccentricallystanding on the foot plate 9 and the fight foot propels; kicking awayfrom the ground level t this foot then stands on the right hand footplate 10 (FIG. 2) and then the left foot carries out the propellingmovement, as we can see on FIG. 5. So progression takes place withalternating standing on the foot plates 9, 10 and kicking away, butnaturally it is not compulsory to kick away and stand always withalternate feet, several kicks may be made by the one foot and then onthe other side. The torsional force made as a consequence of thepropelling is counterbalanced by the force of the ankle of the personusing the device 15 exerted in the opposite direction. After reaching agreater speed it becomes possible for the person using the device 15 tostand on both foot plates 9, 10 continuously and move forwards along asine wave line known from the movement of persons using skateboards. Atthis time the force needed to move forwards can be attained with thealternate left and right movement of the hips—with steeringmovements—and the twisting of the hips, in other words actual steeringmotions involving hip thrusts. If the device is also fitted withhandlebars 13 (FIGS. 1 and 2), the steering movements and themaintenance of the wheel 1 in a vertical plane is ensured by thehandlebars 13 and the connection rod that forms a part of it. Thehandlebars 13 provide the opportunity of fitting brakes and the abilityto brake the device during motion as well, which may increase stabilityin the plane of the wheel 1. The brake may be a block brake as used onnormal bicycles, which may be fitted in front of the upper section ofthe yoke 4 that accepts the wheel 1. The operating cable may be led upto the handbrake grip belonging to the handlebars 13, which may be heldfreely in the hand. Especially in the period of learning to use thedevice the use of an auxiliary structure—sliding insert—marked withreference number 20 as a whole can be practical, which is for thepurpose of reducing friction occurring while propelling the devicebetween the yoke 4 and the knees 21 of the person 15 using the device.The auxiliary structure 20 has a rectangle-shaped, favourablyrectangular-shaped base 22 the inner surface 23 of which touching theknee 21 has a concave curve looking at it from the outside, and itsouter surface 24 touching the yoke 4 while the device is used is astraight, plane surface. In the four corners of the base 22—where it isthe widest as it is shown in FIG. 8—there are hollows 26 in the planesurface 22 in which there are rollers 25 which can be rotated around thez axles of a fixed position so that their surface protrudes from theplane of the surface 24 by a k distance, by a few, practically 1-2 mm-s.For example the h length of the base 2 can be 10-12 cm, and its s widthcan be 4-6 cm. AS a result of the construction described above theauxiliary structure 20 is a coach like construction, which can roll onthe other surface of the yoke 4, and which can be attached to the user'sknees 21 with a releasable connection, for example with hook and loop 28braces 27. As it can be seen in FIGS. 6 and 8 two brace parts 27 a, 27 bare fixed to each auxiliary structure in the area at the ends of theshorter edges of the ase 22, which are taken round the knee 21 andattached to each other with their hook and loop 28, and so the braces 27shown in FIG. 6 are created.

A further construction of the hobby and/or sport device is shown inFIGS. 9-16. This device has two wheels 31, 32 of the same diametersituated positioned immediately next to each other displaced in thelateral direction as compared to each other, overlapping each othernearly to the axles 45, 46; the outside surface of the tyres 41, 42 ispositioned at a minimum distance 1—of about 1-5% of the diameter of thewheel—from the axle of the other wheel. The two wheels 31, 32 areconnected on the one part by a connection element 33 according to FIGS.14-16, made of stiff pipe for example, which has an upside down V shapein the lateral direction, with curved legs 49 a, which are situateddisplaced in the lateral direction as compared to each other in planview, as shown in FIG. 16, connected with a short, horizontal upper rib49 b, so in plan view the connection 33 element is Z-shaped, and pins38, 39 protrude downwards from the upper end of its legs 49 a, andtowards the lower end of the legs 49 a there are blocks 54, 55protruding inwards; the role of these pins and blocks will be describedlater. The connection element 33 encases the wheels 31, 32 with adistance of a few mm-s from the tyres 41, 42, its legs 49 a are in theplane of a wheel 31, 32 each, and they can be as wide as the tyre. Itmust be pointed out that in this case the wheels 31, 32 are bicycle-typewheels, but here the wheel rim 41 a is not connected to the bearinghousings 47, 48 by spokes, but by solid, stiff wheel web-plates 43, 44(FIG. 10).

The above bearing housings 47, 48 should be practically constructed withsleeve pipes the width and bearing capacity of which is bigger than thatof the usual bicycle bearings, and on the two sides it protrudes fromthe plane of the wheels 31, 32 over the side surfaces of the pneumaticrubber tyres 41, 42 seen in a vertical plan. It can be seen well inFIGS. 9, 11 and 12 that a stiff curved supporter 34, 35 is connected toeach protruding end of the bearing housings 47, 48 made of solid (e.g.:metal or plastic) plate or rod, and on the one part its function is tomake it possible to fix the side plates 40 (in FIG. 10 only one of theside plates is shown for better understanding) and on the other part afoot plate is fixed to their upper ends 36, 37 each at a minimum mheight above the ground surface t, that is in this case again thedistance c under the axles 45, 46 to the foot plates 36, 37 shouldpractically be as big as possible.

A bearing 52, 53 to admit the vertical axles 38, 39 of the connectionelement 33, protruding downwards is fixed to each end of the bearinghousings 47, 48—sleeve pipes—protruding inwards. So when the wheels 31,32 are placed next to each other as shown in FIG. 13, and the connectionelement 33, which is Z-shaped in top plane, is adjusted to the bearings52, 53 with its axles 38, 39, a connection is created between the wheels31, 32, where their longitudinal position displaced as compared to eachother in the lateral direction is fixed, and so the wheels can bepropelled closely next to each other, at the same time—as it was shownin FIG. 16—they can be rotated in the opposite direction as compared toeach other, so it is easy to steer the device and there is a possibilityto change directions. However, while the user of the device can easilyturn the wheel 31, 2 outwards by pressing the user's feet in the rightdirection, turning it back from the position shown in FIG. 16 cannot besolved comfortably only with the force expressed by the feet, soaccording to the invention a spring is built in at the bottom 51connecting the foot plates 36, 37, and two springs 50 are built in atthe top to connect the plum stone shaped (FIG. 10) side plates 40overlapping the curved supporters 34, 35—their upper edges—, to make itpossible and easier to turn back the wheels 31, 32 in the basic positionshown in FIG. 13. In order to stop the two wheels bracing up againsteach other as a result of the force of the springs 50, 51, the aboveblocks 56, 57 and 54, 55 are built in; blocks 56 and 54 and blocks 57and 55 are adjusted to each other and they prevent the wheels 31, 32from bracing up against each other.

The curved supporters 34, 35, the foot plates 36, 37 the bearinghousings 47, 48 and the vertical axles 38, 39 of the device—according tothe invention, described above, form a rigid unit on which the wheelscan rotate 31, 32.

The hobby and/or sport device according to FIGS. 9-16 is used so thatthe user propels the device with movements similar to those when using ascooter, and so the user can turn with the device for the purpose ofbalancing or changing directions; turning is made possible by moving thefoot plates 36, 37 from the ankles. By turning the front wheel left thedevice turns left, and by turning the back wheel left the device turnsright. The basic position providing a straight run—as mentioned above—isensured by pulling strings 50, 51. Standing on the foot plates 36, 37the user eccentrically loads the device. As a result of eccentricloading a horizontal reaction force is generated on the knees, whichensures composite action between the device and the user's feet; thesupporting force is taken on and passed onto the device by the sideplates 40. The use of the auxiliary structure 20—a small coach-likestructure—according to FIGS. 6-8, fixed to the knee as a supportingpoint is mainly recommended during the period of learning how to use thehobby and/or sport device. The position of the auxiliary structures 20during use is shown in FIG. 6, where the structural elements describedabove are marked with the reference numbers already used. For the sakeof simplicity the use of the auxiliary structures 20 is only describedwith respect to the device shown in FIGS. 1-5, but obviously they can beused in the same way in connection with the device shown in FIGS. 9-16.The person using the device stands on the foot plates 9, 10 with bothfeet in the position shown in FIG. 6, and supporting against the yoke 4with the auxiliary structures 20 attached to the user's knees 21 withtwo braces 27 each, the user moves rolling on the wheel 1. The supportbetween the yoke 4 and the knees 21 provided by the lowfriction—rolling—intermediate auxiliary structure 20 makes it possiblefor the user to place the centre of gravity of the user's body forwardor to the rear to a smaller extent, which makes balancing easier andincreases stability while moving.

The advantage of the invention is that the resistance of the device islow—first of all due to the large wheel diameter—, it is significantlylower than that of other similar sport and/or hobby devices such asskateboards, and it can be easily steered with small ankle movements.Due to the fact that when the user steps off the vehicle, it tips overimmediately, stops rolling and stays lying on the ground, it representsa significantly lower danger of accident than skateboards that run looseand roll on on their own in this case. The advantage of the auxiliarystructure is that it makes it easier to learn to use the vehicle.

Obviously the invention is not restricted to the construction example ofthe device described above, but it can be constructed in several wayswithin the sphere of protection defined by the claims.

1. A sport device that is propelled by kicking away from a solidsurface, comprising: a wheel (1) that can be rotated around an axle (3);foot plates (9, 10) extending outwards under the level of said axle (3)by said wheel (1) having two side plates (7, 8) fixed to the axle (3) ofthe wheel (1), and the foot plates (9, 10) rigidly fixed to a lower endrange of the side plates (7, 8), the lower end range of the side platesbeing formed so that the side plates (7, 8) extend upwards; and a firstsupporting plate (12) and a second supporting plate (12) that arerespectively coupled to each of the side plates (7, 8), the first andsecond supporting plates being parallel to the axle (3) and extendinglateral from each of the side plates.
 2. The sport device according toclaim 1 wherein the side plates (7, 8) are fixed together as a yoke (4,4 a) via a connection rib (14) or ribs (18, 19) running along theiredges.
 3. The sport device according to claim 1 or 2 wherein the ends ofthe wheel (1) and axle (3) are fixed into thickened plate parts (7 a, 8a) of the side plates (7, 8).
 4. The sport device according to claim 3wherein the foot plates (9, 10) are positioned at a predetermineddistance (c) from the axle (3) of the wheel (1) ensuring operation ofthe device at a distance (m) from ground level (t) in an operatingposition of the device.
 5. The sport device according to claim 4 whereinthe side plates (7, 8) are circular plates of a form and size thatessentially conforms to that of the form of the wheel, and a curved,convex, as seen from the outside, connection rib (14) runs withoutinterruption along the edges of the side plates (7, 8), except for anopening (11) allowing the wheel rim (2 a) to protrude.
 6. The sportdevice according to claim 4 wherein the side plates (7, 8) are formed sothat they only partly cover from the side of the wheel (1),advantageously in such a way that in the vicinity of the wheel (1) axle(3) their width is the smallest, and from this range their widthincreases downwards and upwards.